Method and system for classification of photo-plethysmographically detected respiratory effort

Abstract

Embodiments disclosed herein may include systems and methods for determining a patient's respiratory effort and blood oxygen saturation based on data acquired from a pulse oximetry sensor and analyzing the parameters in conjunction with each other. For example, the respiratory effort may be determined based on a photo-plethysmographic waveform generated from light attenuation detected by the sensor, and the blood oxygen saturation may be a pulse -based estimate of arterial blood oxygen saturation determined from the detected attenuation. Analysis of the parameters may enable detection and classification of apnea (e.g., obstructive or central) or another underlying cause for respiratory instability. Furthermore, the measured respiratory effort may be compared to respiratory effort supplied by a ventilator to ensure proper sensor placement before enabling automatic adjustment of ventilator settings.

1. A method performed by a photo-plethysmographic monitor, the method comprising:
 determining a respiratory effort of a patient based at least in part on a photo-plethysmographic signal; 
 calculating a value of a physiological parameter of the patient based at least in part on the photo-plethysmographic signal; 
 determining whether the patient is experiencing an apneic event based at least in part on the respiratory effort and the value of the physiological parameter; and 
 distinguishing the apneic event from a measurement artifact based at least in part on analysis of the respiratory effort and the value of the physiological parameter in conjunction with heart rate patterns of the patient. 
 
     
     
       2. The method of  claim 1 , wherein determining the respiratory effort and calculating the value of the physiological parameter comprise analyzing light attenuation data from a non-invasive pulse oximetry sensor. 
     
     
       3. The method of  claim 1 , comprising characterizing the apneic event based at least in part on the respiratory effort and the value of the physiological parameter. 
     
     
       4. The method of  claim 3 , wherein characterizing the apneic event comprises analyzing a history of repetitive changes in the respiratory effort and/or changes in the value of the physiological parameter, and/or combinations thereof. 
     
     
       5. The method of  claim 1 , wherein calculating the value of the physiological parameter comprises determining a pulse-based estimate of arterial blood oxygen saturation. 
     
     
       6. The method of  claim 1 , wherein determining the respiratory effort comprises determining an indication of a respiratory minute volume, a respiratory rate, a tidal volume, a diaphragmatic or intrathoracic pressure variation, and/or a combination thereof. 
     
     
       7. A system, comprising:
 a sensor configured to emit light into tissue and to measure attenuation of the light from the tissue; 
 a monitor configured to:
 generate a photo-plethysmographic waveform based at least in part upon the measured attenuation; 
 determine a respiratory effort of a patient based at least in part on the photo-plethysmographic waveform; 
 estimate a value of a physiological parameter of the patient based at least in part on the photo-plethysmographic waveform; 
 determine whether the patient is experiencing an apneic event based at least in part on the respiratory effort and the value of the physiological parameter; and 
 distinguish the apneic event from a measurement artifact based at least in part on analysis of the respiratory effort and the value of the physiological parameter in conjunction with heart rate patterns of the patient. 
 
 
     
     
       8. The system of  claim 7 , wherein the monitor is configured to characterize the apneic event based at least in part on the respiratory effort and the value of the physiological parameter. 
     
     
       9. The system of  claim 8 , wherein the monitor is further configured to analyze a history of repetitive changes in the respiratory effort and/or changes in the value of the physiological parameter, and/or combinations thereof. 
     
     
       10. The system of  claim 7 , wherein the monitor is further configured to analyze light attenuation data from a non-invasive pulse oximetry sensor. 
     
     
       11. The system of  claim 7 , wherein the monitor is further configured to determine a pulse-based estimate of arterial blood oxygen saturation. 
     
     
       12. The system of  claim 7 , wherein the monitor is further configured to determine an indication of a respiratory minute volume, a respiratory rate, a tidal volume, a diaphragmatic or intrathoracic pressure variation, and/or a combination thereof.